lkml.org 
[lkml]   [2008]   [Jun]   [17]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [Bad page] trying to free locked page? (Re: [PATCH][RFC] fix kernel BUG at mm/migrate.c:719! in 2.6.26-rc5-mm3)
From
Date
On Tue, 2008-06-17 at 18:15 +0900, Daisuke Nishimura wrote:
> On Tue, 17 Jun 2008 18:03:14 +0900, KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> wrote:
> > On Tue, 17 Jun 2008 16:47:09 +0900
> > Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> wrote:
> >
> > > On Tue, 17 Jun 2008 16:35:01 +0900, Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> wrote:
> > > > Hi.
> > > >
> > > > I got this bug while migrating pages only a few times
> > > > via memory_migrate of cpuset.
> > > >
> > > > Unfortunately, even if this patch is applied,
> > > > I got bad_page problem after hundreds times of page migration
> > > > (I'll report it in another mail).
> > > > But I believe something like this patch is needed anyway.
> > > >
> > >
> > > I got bad_page after hundreds times of page migration.
> > > It seems that a locked page is being freed.

I'm seeing *mlocked* pages [PG_mlocked] being freed now with my stress
load, with just the "if(!page->mapping) { } clause removed, as proposed
in your rfc patch in previous mail. Need to investigate this...
I'm not seeing *locked* pages [PG_lock], tho'. From your stack trace,
it appears that migrate_page() left locked pages on the list of pages to
be putback. The pages get locked and unlocked in unmap_and_move(). I
haven't found a path [yet] where the page can be returned still locked.
I think I need to duplicate the problem.

> > >
> > Good catch, and I think your investigation in the last e-mail was correct.
> > I'd like to dig this...but it seems some kind of big fix is necessary.
> > Did this happen under page-migraion by cpuset-task-move test ?
> >
> Yes.
>
> I made 2 cpuset directories, run some processes in each cpusets,
> and run a script like below infinitely to move tasks and migrate pages.

What processes/tests do you run in each cpuset?

>
> ---
> #!/bin/bash
>
> G1=$1
> G2=$2
>
> move_task()
> {
> for pid in $1
> do
> echo $pid >$2/tasks 2>/dev/null
> done
> }
>
> G1_TASK=`cat ${G1}/tasks`
> G2_TASK=`cat ${G2}/tasks`
>
> move_task "${G1_TASK}" ${G2} &
> move_task "${G2_TASK}" ${G1} &
>
> wait
> ---
>
> I got this bad_page after running this script for about 600 times.
>





\
 
 \ /
  Last update: 2008-06-17 20:31    [from the cache]
©2003-2011 Jasper Spaans